performance: 0.982
graphic: 0.919
device: 0.633
arm: 0.480
semantic: 0.456
ppc: 0.405
mistranslation: 0.391
register: 0.354
permissions: 0.346
i386: 0.327
socket: 0.325
architecture: 0.322
vnc: 0.308
boot: 0.258
user-level: 0.248
PID: 0.237
risc-v: 0.227
network: 0.210
x86: 0.205
VMM: 0.174
kernel: 0.174
virtual: 0.157
debug: 0.149
peripherals: 0.145
files: 0.137
assembly: 0.123
hypervisor: 0.117
TCG: 0.111
KVM: 0.033

Poor console performance in Windows 7

As part of its conformance test suite, Wine tests the behavior of the Windows console API. Part of this test involves opening a test console and scrolling things around. The test probably does not need to perform that many scroll operations to achieve its goal. However as is it illustrates a significant performance issue in QEmu. Unfortunately it does so by timing out (the tests must run in less than 2 minutes). Here are the run times on a few configurations:

 10s - QEmu 1.4 + Q9450@2.6GHz + Windows XP + QXL + QXL driver
  8s - QEmu 1.12 + Opteron 6128 + Windows XP + QXL + QXL driver
127s - QEmu 1.12 + Opteron 6128 + Windows 7 + cirrus + vga driver
127s - QEmu 1.12 + Opteron 6128 + Windows 7 + QXL + QXL driver
147s - QEmu 1.12 + Opteron 6128 + Windows 7 + vmvga + vga driver
145s - QEmu 1.12 + Opteron 6128 + Windows 7 + vmvga + vmware driver (xpdm, no better with all graphics effects disabled)

 10s - Metal + Atom N270 + Windows XP + GMA 950 + Intel driver
  6s - Metal + i5-3317U + Windows 8 + HD4000 + Intel driver
  3s - VMware + Q9450@2.6GHz + Windows XP + vmvga + vmware driver
 65s - VMware + Q9450@2.6GHz + Windows 7 + vmvga + vmware driver

So when running on the bare metal all versions of Windows are about as fast. However in QEmu Windows 7 is almost 16 times slower than Windows XP! VMware is impacted too but it's still maintains a good lead in performance.

Disabling all graphics effects did not help so it's not clear that the fault lies with Windows 7's compositing desktop window manager. Maybe it has to do with the lack of a proper wddm driver?



Triaging old bug tickets... can you still reproduce this issue with the latest version of QEMU? Or could we close this ticket nowadays?

It does seem to be ok now. The test did get simplified to remove parts that were mostly redundant so it runs faster now. But still it now takes the same time, 7 seconds, on the VMware and QEMU Windows 7 VMs. So as far as I'm concerned this can be closed.